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Identity (NIP-06 / NIP-49)

Summary. Each wallet has a Nostr keypair that is its payment identity. The secret key is stored encrypted at rest (NIP-49 ncryptsec, owner-only file permissions). Crucially, this key is separate from your Grin seed, so you can rotate your identity to stay unlinkable without ever touching your funds. A wallet can also hold several identities at once, all listening together; see Multiple identities.

Motivation

Two design tensions shape Goblin’s identity:

  1. Linkability. If your payment identity were derived from your wallet seed, it would be permanent: every payment forever tied to one key. Goblin wants you to be able to start fresh. So the nostr key is independent and rotatable.
  2. Safety at rest. The secret key sits on a phone. It must never be on disk in the clear, and the file must not be world-readable.

How it works

Your identity lives in wallet_data/nostr/identity.json, written with Unix mode 0600 inside a 0700 directory. Inside, the secret key is a NIP-49 ncryptsec: a bech32 blob encrypted with your wallet password via scrypt (work factor log_N = 16, ~64 MiB, interactive grade). The file also stores your npub in the clear (so the UI can show “you” before you’ve unlocked), your nip05 name if you’ve claimed one, an anonymous flag, and prev_npubs, a history of keys you’ve rotated away from.

There are three ways an identity comes to exist (IdentitySource):

  • Random (default): a brand-new independent key (Keys::generate). Unlinkable to your seed and to any other wallet.
  • Imported: you paste an nsec or restore an encrypted backup file, adopting an existing identity (name and history included).
  • Derived: a NIP-06 seed-derived key. Kept for legacy wallets; new wallets use Random.

Starting a fresh, unlinkable key does not need a dedicated rotate action, and the old one was removed: it was only a random add-and-switch that also released your name, adding nothing over the identity switcher. To present as a new independent key you add an identity (a random Keys::generate key, unlinkable to your seed and your other identities) and switch to it, all without re-seeding, so your Grin balance is untouched. Adding a new key does not carry your username or profile to it; to keep a name on a new key, transfer the name through the authority. See Multiple identities. The prev_npubs field still records keys a wallet has moved away from.

Screenshot: Settings → Identity card (Copy npub, Back up to a file, and the identity switcher), dark theme.

Backup & restore. As of Build 158 the backup (Settings → Advanced, under Advanced nostr settings, captioned “Contains your wallet and all identities.”) writes one sealed, encrypted .backup file that holds both your Grin money seed and every identity the wallet holds, with the active one marked. One file now moves a whole wallet, funds and names together, so there is no longer a separate seed-phrase-plus-identity-file dance. Restoring it is a single step in onboarding: the restore flow’s “Choose a .backup file” picker takes the file, you unlock it with the wallet password, and it fills the 24-word recovery grid for you; once the wallet opens, the identities restore automatically (a “Restoring your identities…” card shows the progress). Older single-identity backups still restore: importing one adopts that one identity (name and history included), decrypting with its export-time password and re-encrypting under the new wallet’s password.

Logging in to other nostr apps. Settings → Advanced → Nostr key reveals your nsec behind your wallet password: enter the password, then copy the key or show it as a QR. Scanning that QR (or pasting the copied nsec) into another nostr app’s private-key login, for example magick.market, signs you in with the same identity your wallet uses. The key is derived on demand behind the password and never persisted in the clear; a wrong password reveals nothing.

Reference

  • IdentitySource enum and the NostrIdentity struct: goblin/src/nostr/identity.rs. Fields: ncryptsec, npub, nip05, anonymous, prev_npubs.
  • Encryption at rest: NIP-49 ncryptsec, scrypt NCRYPTSEC_LOG_N = 16.
  • File safety: write_private() (Unix 0600), restrict_dir() (0700); stored at wallet_data/nostr/identity.json.
  • Key derivation for the legacy Derived source: derive_keys() (NIP-06 BIP-44 path).
  • Rotation/import/backup UI: RotateState / ImportState / BackupState flows in goblin/src/gui/views/goblin/mod.rs; onboarding import in onboarding.rs (OnbImport).

References